Server algorithms to improve space based authentication

Abstract

A system and methods for location authentication are presented. An estimated server signal is estimated based on a generated known code signal, and a client received satellite signal is received from a client device. The client received satellite signal is compared to the estimated server signal to provide a comparison result.

The invention claimed is: 
     
       1. A method for location authentication, the method comprising:
 constructing an estimated server unknown high-rate encrypted code signal based on an estimated server unknown low-rate code signal and a generated known high-rate code signal; 
 receiving a client received unknown high-rate encrypted code satellite signal from a client device; and 
 comparing the client received unknown high-rate encrypted code satellite signal to the estimated server unknown high-rate encrypted code signal to provide a code comparison result. 
 
     
     
       2. The method of  claim 1 , further comprising authenticating a location of the client device based on the code comparison result. 
     
     
       3. The method of  claim 2 , wherein:
 the client device is allowed access to a protected resource if the location of the client device is valid; and 
 the client device is not allowed access to the protected resource if the location of the client device is invalid. 
 
     
     
       4. The method of  claim 1 , further comprising:
 receiving a server received unknown high-rate coded satellite signal comprising a public code and an encrypted code from a satellite receiver device, the encrypted code comprising a product of a unknown low-rate code and a known high-rate code synchronized to the public code; 
 estimating a time synchronization of the public code to provide an estimated code time synchronization; 
 generating the known high-rate code based on the estimated code time synchronization to provide an estimated server known high-rate code; and 
 removing the estimated server known high-rate code from the encrypted code of the server received coded satellite signal to provide the estimated server unknown low-rate code signal. 
 
     
     
       5. The method of  claim 4 , further comprising the generated known high-rate code signal comprising the estimated server known high-rate code. 
     
     
       6. The method of  claim 4 , wherein the public code comprises a GPS C/A code, the encrypted code comprises a GPS P(Y) code, the unknown low-rate code comprises a GPS W code, and the known high-rate code comprises a GPS P code. 
     
     
       7. The method of  claim 4 , wherein the server received unknown high-rate coded satellite signal is transmitted from at least one of the group consisting of: an LEO satellite, an MEO satellite, a GEO satellite, a Global Navigation Satellite System (GNSS) satellite, and a Global Positioning System satellite. 
     
     
       8. The method of  claim 1 , further comprising filtering the estimated server unknown high-rate encrypted code signal. 
     
     
       9. The method of  claim 1 , further comprising synchronizing the estimated server unknown high-rate encrypted code signal to the client received unknown high-rate encrypted code satellite signal. 
     
     
       10. The method of  claim 1 , further comprising:
 estimating a coarse unknown low-rate code time synchronization based on the estimated server unknown low-rate code signal and the client received unknown high-rate encrypted code satellite signal; 
 estimating a fine unknown low-rate code time synchronization based on the coarse unknown low-rate code time synchronization and the client received unknown high-rate encrypted code satellite signal; 
 constructing the generated known high-rate code signal based on the fine unknown low-rate code time synchronization; and 
 constructing the estimated server unknown high-rate encrypted code signal further based on the fine unknown low-rate code time synchronization. 
 
     
     
       11. A location authentication system comprising:
 a server comprising a processor and a memory storing instructions, that when executed by the processor, causes the server to:
 construct an estimated server unknown high-rate encrypted code signal based on an estimated server unknown low-rate code signal and a generated known high-rate code signal; 
 receive a client received unknown high-rate encrypted code satellite signal from a client device; 
 compare the client received unknown high-rate encrypted code satellite signal to the estimated server unknown high-rate encrypted code signal to provide a code comparison result; and 
 
 authenticate a location of the client device based on the code comparison result. 
 
     
     
       12. The system of  claim 11 , wherein the server is further configured to:
 receive a server received unknown high-rate coded satellite signal comprising a public code and an encrypted code from a satellite receiver device, the encrypted code comprising a product of a unknown low-rate code and a known high-rate code synchronized to the public code; 
 estimate a time synchronization of the public code to provide an estimated code time synchronization; 
 generate the known high-rate code based on the estimated code time synchronization to provide an estimated server known high-rate code; and 
 remove the estimated server known high-rate code from the encrypted code of the server received coded satellite signal to provide the estimated server unknown low-rate code signal. 
 
     
     
       13. The system of  claim 11 , wherein the server is further configured to:
 estimate a coarse unknown low-rate code time synchronization based on the estimated server unknown low-rate code signal and the client received unknown high-rate encrypted code satellite signal; 
 estimate a fine unknown low-rate code time synchronization based on the coarse unknown low-rate code time synchronization and the client received unknown high-rate encrypted code satellite signal; 
 construct the generated known high-rate code signal based on the fine unknown low-rate code time synchronization; and 
 construct the estimated server unknown high-rate encrypted code signal further based on the fine unknown low-rate code time synchronization. 
 
     
     
       14. A location authentication system comprising:
 a server comprising a processor and a memory storing instructions, that when executed by the processor, causes the server to:
 construct an estimated server unknown high-rate encrypted code signal based on an estimated server unknown low-rate code signal and a generated known high-rate code signal; 
 receive a client received unknown high-rate encrypted code satellite signal from a client device; and 
 compare the client received unknown high-rate encrypted code satellite signal to the estimated server unknown high-rate encrypted code signal to provide a code comparison result. 
 
 
     
     
       15. The system of  claim 14 , wherein the server is further configured to:
 receive a server received unknown high-rate coded satellite signal comprising a public code and an encrypted code from a satellite receiver device, the encrypted code comprising a product of a unknown low-rate code and a known high-rate code synchronized to the public code; 
 estimate a time synchronization of the public code to provide an estimated code time synchronization; 
 generate the known high-rate code based on the estimated code time synchronization to provide an estimated server known high-rate code; and 
 remove the estimated server known high-rate code from the encrypted code of the server received coded satellite signal to provide the estimated server unknown low-rate code signal. 
 
     
     
       16. The system of  claim 15 , wherein the generated known high-rate code signal comprises the estimated server known high-rate code. 
     
     
       17. The system of  claim 15 , wherein the public code comprises a GPS C/A code, the encrypted code comprises a GPS P(Y) code, the unknown low-rate code comprises a GPS W code, and the known high-rate code comprises a GPS P code. 
     
     
       18. The system of  claim 14 , wherein the server is further configured to:
 estimate a coarse unknown low-rate code time synchronization based on the estimated server unknown low-rate code signal and the client received unknown high-rate encrypted code satellite signal; 
 estimate a fine unknown low-rate code time synchronization based on the coarse unknown low-rate code time synchronization and the client received unknown high-rate encrypted code satellite signal; 
 construct the generated known high-rate code signal based on the fine unknown low-rate code time synchronization; and 
 construct the estimated server unknown high-rate encrypted code signal further based on the fine unknown low-rate code time synchronization. 
 
     
     
       19. The system of  claim 14 , wherein the server is further configured to:
 filter the estimated server unknown high-rate encrypted code signal. 
 
     
     
       20. The system of  claim 14 , wherein the server is further configured to:
 synchronize the estimated server unknown high-rate encrypted code signal to the client received unknown high-rate encrypted code satellite signal.